code: def test_collate_classes(self) -> None:
      x = torch.randn(self.data_size, self.dimension)
      y = torch.randint(
          low=0, high=self.num_classes, size=(self.data_size,)
      )
  
      dataset = TensorDataset(x, y)
      data_loader = DPDataLoader(dataset, sample_rate=1e-5)
  
      x_b, y_b = next(iter(data_loader))
      self.assertEqual(x_b.size(0), 0)
      self.assertEqual(y_b.size(0), 0)
  
file_path: opacus/opacus/tests/dpdataloader_test.py
imports: import unittest
  import torch
  from opacus.data_loader import DPDataLoader
  from torch.utils.data import DataLoader, TensorDataset
label_desc: Use image node_id 2 for calling the DPDataLoaderTest obj's underlying member method code with example usage: obj.test_collate_classes() without return types